The Whitehead Institute requests $500,000 for the purchase of a FEI Technai 12 Spirit BioTwin TEM to be housed in the WM Keck Microscope Facility. The FEI TEM will up-grade the TEM services of the facility by replacing a twenty-year old Phillips 410 TEM. The 410 is nearing the end of its operational lifetime and maintenance is becoming difficult. More importantly, new generation FEI TEMs provide semi-automated operations for users and digital CCD-based imaging speeds and simplifies image capture, processing, and analysis for users and TEM technical staff. As an instrument in a core microscope facility, the TEM is widely used by Wl researchers. In addition, the same TEM is the only general use biological TEM on the MIT campus and serves labs in biology, bioengineering, engineering, chemistry, and other MIT departments. Furthermore, a significant number of researchers from the Boston-area also use the TEM. Thus, an up- graded TEM would benefit a significantly large research base. The proposal describes the research of six NIH-supported researchers and one new assistant professor at Tufts U. which does not have a biological TEM; To support the FEI Technai TEM, the Wl is committing an annual budget of $42,652 for an EM technician salary and maintenance contract. Furthermore, the Wl will pay $53,910 toward the purchase, shipping, and duty of the microscope. [unreadable] [unreadable]